Beer is a $100 billion industry in the country, selling over 6 trillion gallons per year. Beer has gotten fancy, and sales are exploding up 50%. What is that doing to the beer business? We welcome the nutrition and wellness editor to "nightline." &#9834; &#9834; it is one of america's favorite pasttimes, celebrating summer with a cold one, beer is having a big moment. A revolution of sorts. From festivals. I'm here to taste the beer. To tours. To beer gardens. And now I have a greater appreciation of all the work that goes into it. In the old days, beer was the down scale beverage of choice with down to earth characters like the one in animal house. Don't cost nothing. Or smoky, smoky and the bandit. But these days, beer has taken as seriously as fine wine, and there is a new crop of snobs to tell you about it. A little bit of pineapple and mango. Reporter: Rating hundred of varieties, there are experts suggesting food pairings. These are great with fajitas. Reporter: This is not your ordinary six-pack, people are increasing searching out beers to experiment with the flavor. Creating what is known as craft beer. Craft beer, exploding, big breweries are looking at that, trying to make the more local fresh products. Reporter: In the past year alone, hundreds of new craft breweries have popped up all over the u.S., With big beer sales on the decline, big dogs like bud and coors are scrambling to get involved in the craft craze. If there was ever a beer craze, this is how miller would have wanted it to go. But these days, a real beer war is brewing, between the giants like busch and micro-breweries. This forces us to get better. And I tell people drink the beer, don't drink the advertising or the marketing. And may the best beer win. Reporter: The maker of bud, who owns nearly 50% of the american market now admits they were complacent. But we were not necessarily paying attention to some of the things happening around us. Reporter: To see the front lines of the beer battle, we hopped on a beer bus. A party for beer. Reporter: Here, people are serious about their beer. I like miller high life. The champagne of beers. We have more than a appreciation. Definitely, I can't go home and drink it. Reporter: We started our journey at the largest craft beer maker in the country. Boston beer company. Home of sam adams. One of the things that I as a brewer love to do is take beer where no beer has gone before. Reporter: Jim cook started to brew in his kitchen 30 years ago. Now he ships 2.7 million barrels a year, with over 50 different kinds of brews. These are hops. They give beer its spiciness and the aroma. Reporter: But often it comes at a price, costing much more than the regular brands, clearly, customers are paying up. And busch wants in, they're buying up craft breweries like this one in chicago. We're the rich uncle that provides them the resources they need and a team there that a continues to innovate. Some of the critics may say they don't put their name, bud, on the label. I think that is kind of ridiculous. People are going to find out they make it. And it is a source of pride for us when they do find that anheuser busch makes them. I get a little bit of chuckle when the largest brewer in the world wants to pretend like they're little sam adams. Even though it is kind of annoying to have the big ones pretending they're us, what are you going to do? If people start with the copy cat beer from the big brewers, well, they will soon graduate and discover the real thing. Reporter: The brooklyn brewery is producing only a tiny fraction of beer compared to the big guys. But the brew master says, they're still winning. We're making ten times more beer than we were three years ago. This movement is happening now because our entire culture is moving towards more flavor. Reporter: But anheuser busch claims they are still the king of beer. There is a reason why we sell as much beer as we do. They like it, and it is good. Does it annoy you when people refer to it as the yellow grainy stuff. We take it with a grain of salt. Those guys know how hard it is to make a lager. Reporter: It is clear this is here to stay. And our thanks to you, dave. Well, next, more than 10

This transcript has been automatically generated and may not be 100% accurate.